Conventionally, a hose line composed of a plurality of hoses connected end-to-end is used for loading a tanker with oil or the like, or unloading the tanker, because the tanker is generally moored offshore.
In the case where a hose used for the hose line is damaged in an emergency, oil leaks out from the hose line, and serious environmental pollution results. Therefore, the hose used for the hose line has a double construction in which an auxiliary pressure cord layer is provided outside the main pressure cord layer which provides a chamber into which fluid that has leaked through the main pressure layer flows. In the case where the main pressure cord layer is damaged, the fluid that leaks out from the main pressure cord layer is retained in the chamber enclosed by the auxiliary pressure cord layer. Accordingly, in the prior art, if the outer appearance of the hose is visually inspected to be changed, the damage in the hose is determined.
In this connection, when the hose is used in the sea, it is impossible to determine the occurrence of damage visually. Therefore, a detector is provided in the hose, by which a change in pressure of the fluid that has leaked out from the main pressure cord layer into the chamber is detected, and a signal sent from the detector is received by a receiver installed on the sea or ground, so that the occurrence of damage of the main pressure cord layer is determined.
When the hose is used in the sea as described above, it is necessary to provide auxiliary apparatus such as a detector and receiver. Therefore, the installation of the hose is complicated, and the cost of the hose is greatly increased.
Furthermore, the detector tends to be damaged and malfunctions tend to occur, so that the aforementioned detection system lacks reliability when it is used over a long period of time.